If anyone is looking for a travel agent for the Cancun/Riviera Maya Area, I highly recommend Kathryn of Kathryn's Travels. She herself got married on Isla Mujeres, where we are getting married.
Kathryn's Travel - HOME
I also highly recommend that you consider buying a map from the Map Chick if you are traveling to any of these areas. She sells maps for Isla Mujeres, Cancun, Playa del Carmen, the Riviera Maya and Cozumel. They are way better and more informative than any guide book I have bought. And they are only $10.
MapChick's travel tips